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NORTHERN TERRITORY GEOLOGICAL SURVEY
Maximising the value of NVCL HyLogger
data: Understanding automated
mineralogical interpretations
Belinda Smith, Mark Berman, Ralph Bottrill, Tania Dhu, Suraj Gopalakrishnan,
Georgina Gordon, David Green, Jon Huntington, Alan Mauger
NORTHERN TERRITORY GEOLOGICAL SURVEY
Introduction
• Aims– Understanding what the HyLogging NVCL is
– New to HyLogging – understanding what it is and what it is
telling you
– HyLogger User – understanding the different levels of
processing
– Increase understanding of the methods and processes
behind the mineral outputs from TSG.
NORTHERN TERRITORY GEOLOGICAL SURVEY
• AuScope NVCL initiative – started
in 2007
– Australia-wide drillcore
database comprising high-
resolution imagery and
mineralogical data from
spectroscopic scanning
– facilitate geoscience research
– data available to the public via
a web-based delivery system
National Virtual Core Library (NVCL)
Access Infrastructure
MaterialInfrastructure
Infrastructure
Technology Infrastructure
Human
2
1
3
4
NORTHERN TERRITORY GEOLOGICAL SURVEY
AuScope Portalhttp://portal.auscope.org/portal/gmap.html
NORTHERN TERRITORY GEOLOGICAL SURVEY
HyLogging basics• Produces images of the
core
• Produces reflectance
spectra (matched to
minerals)
• Improves objectivity of
core logging
• Enhances geological
understanding
• Sampling every 8mm x
8mm width for whole
length of core
• Wallara 1 (1668m / 349
core trays) = 218,125
spectra
Multiple data streams
integrated in TSG software
NORTHERN TERRITORY GEOLOGICAL SURVEY
• Voluminous data with 100,000s spectra in a single drillhole
• Hundreds of drillholes; thousands of metres nationwide
• Automate the mineral matching with;– TSA (The Spectral Assistant). Refine with;
– Restricting minerals in TSA (uTSA)
– Creating domains in TSA (dTSA)
– Using CLS with domains
Automated Mineralogical Interpretation
NORTHERN TERRITORY GEOLOGICAL SURVEY
Mineralogical Interpretation of HyLogger Data
The Spectral Assistant (TSA) – System MatchesAlgorithm matching to whole spectral library
TSA – User Matches (uTSA)
Manual restriction of unlikely mineralsMinerals match across whole hole
sTSA
ALL DATASETS
Domaining (dTSA)
CLS
Constrained Least
Squares
External
Validation
Creating and using scalars
(XRD, petrography, SEM)
uTSA +/- scalars
Good for basement / seds drillholes
Recommended for TIR spectra
processing (non-unique spectra) Steps are not sequential
NORTHERN TERRITORY GEOLOGICAL SURVEY
TSA mineral matching• ‘Unmixes’ spectral response into mineral
mixes of 2 (SWIR) or 3 (TIR) using an
algorithm
• Only matches to minerals in the library
• If a mineral isn’t active in that wavelength
range, you won’t see it
• If there’s more than 2 - 3 (SWIR) or 3 -4
(TIR) minerals per spectrometer you won’t
see them
• It is NOT an assay! You get a indication of
minerals present, NOT an absolute
quantifiable modal value.
• Nonetheless valuable as nothing else is as
fast.
NORTHERN TERRITORY GEOLOGICAL SURVEY
• Automated process which can handle (simple) mineral
mixtures very quickly
• Detailed: mineral match output for each spectrum
(8mm*18mm)
• Results returned as mineral names (rather than wavelengths)
so outputs easily understood by geoscientists
• Summary overviews can show bulk mineral changes in the
entire drilled length
Strengths of TSA Mineral Outputs
NORTHERN TERRITORY GEOLOGICAL SURVEY
Detailed TSA outputs
NORTHERN TERRITORY GEOLOGICAL SURVEY
TSA results…. sTSA Summary
Black shales, dolomitic quartz sandstones metamorphosed basementdolostones
epidote
talc
SYSTEM TSA
has
‘unsupervised/
unedited’
watermark.
Mathematical
fit; no geology
used.
NORTHERN TERRITORY GEOLOGICAL SURVEY
TSA results…. uTSA Summary
quartz
calcite
calcitedolomite
chlorite
amphibole
USER (uTSA) –
has been
refined to
exclude unlikely
minerals when
spectral
matching.
BUT sediments
show epidote,
phlogopite
(can’t exclude
because they’re
in basement).
talc
gone
epidote still present
phlogopite
NORTHERN TERRITORY GEOLOGICAL SURVEY
TSA results…. uTSA Summary DOMAINED
quartz
calcite
calcite dolomite chlorite
amphibole
Results have
been
DOMAINED; no
phlogopite,
epidote in
sediments but
is in basement. epidote gone
talc, phlogopite removed
epidote still here
NORTHERN TERRITORY GEOLOGICAL SURVEY
TSG SOFTWARE – mineral matching (TSA)
Well-crystalline kaolinite 100%SRSS = 146
Petermann Sandstone; from LA05DD01Quartz 100%Does not see kaolinite feature Appears to be a well-sorted sandstone
TSA SWIR response of wx kaolinite only
TSA TIR response of quartz only
SWIR can’t ‘see’ quartz
CLS has quartz AND kaolinite
SWIR & TIR results
93% quartz, 6% kaolinite
black = spectrumblue = modelled spectrum
black = spectrumblue = modelled spectrum
black = spectrumgreen = modelled spectrum
SWIR TSA says..
• FeMg Chlorite
• Phengitic mica
TIR Spectra Mixing
non-uniquenessTIR TSA
Result
Slide courtesy Andy Green, OTBC Pty Ltd
NORTHERN TERRITORY GEOLOGICAL SURVEY
• TSA can’t effectively look at as many mixtures in the TIR
(n=3). CLS can return 6 – 7 mixtures
• TSA has difficulty with non-unique spectra
• TSA concentrates on getting the best fit over the whole
spectrum and may miss small features (think kaolinite in
Petermann Sandstone)
• CLS has to use a manually selected Restricted Mineral
Set (optional in TSA)
CLS vs. TSA in the TIR
NORTHERN TERRITORY GEOLOGICAL SURVEY
• HyLogger returns voluminous whole-of-drillhole measurements vs. individual point sampling done with hand-held devices
• HyLog FIRST, destructive sampling SECOND (when wanting to compare mineral results from two techniques)
• HyLogger weakness is quantifiable mineralogy
• Mineralogy validation ongoing; many Surveys have in-house XRD facilities
HyLogging vs. other mineralogy outputs: XRD / EDAX / Petrography
NORTHERN TERRITORY GEOLOGICAL SURVEY
• Relatively semi-quantitative– May depend on absorption co-efficient
– Linear surface measurement (not whole core)
– Does not deal well with complex mixtures
– Proportions are RELATIVE…. If a dominant mineral is inactive in that wavelength range, then it won’t be returned as a mineral match from that spectrometer
– If a mineral is < 15% of the mineral mix, it won’t be listed (default)
TSA Mineral Mix Proportions
NORTHERN TERRITORY GEOLOGICAL SURVEY
• Core quality (look at imagery)
• Complexity of mineral
assemblage
• Degree of processing
• Incorporating scalars into the
processing workflow
• Domaining
• External validation
Factors influencing confidence levels of automated mineral modelling
The Spectral Assistant (TSA) – System Matches
Algorithm matching to whole spectral library
TSA – User Matches (uTSA)
Manual restriction of unlikely minerals
Domaining (dTSA)
CLS
Combined Least
Squares
External
Validation
Creating and using scalars
NORTHERN TERRITORY GEOLOGICAL SURVEY
• Good for voluminous whole-of-drillhole
data
• Good for mineral matches of 2 – 3
minerals
• Good for stratigraphic
boundaries/correlations; alteration haloes
• Increased level of processing (restricted
mineral matching of algorithm using
context and common sense) gives
increased confidence in the results
• Need to learn to recognise what is likely,
what is real; what needs validation with
external techniques
HyLogger Data – ‘fit for purpose’?
The Spectral Assistant (TSA) – System Matches
Algorithm matching to whole spectral library
TSA – User Matches (uTSA)
Manual restriction of unlikely minerals
Minerals match across whole hole
Domaining (dTSA)
CLS
Combined Least
Squares
External
Validation
Creating and using scalars
NORTHERN TERRITORY GEOLOGICAL SURVEY
• Use of scalars• Look at the imagery (core quality)• Look at the spectral fit to the algorithm• Validate using complementary
techniques (XRD, petrography, etc)• Use your geological knowledge:
– ‘am I likely to see that mineral in that geological environment?’
– is that mineral responsive in that wavelength range? (think quartz/ feldspars not showing in SWIR)
– is that mineral in the TSA library?
Validate the mineral response
NORTHERN TERRITORY GEOLOGICAL SURVEY
• HyLogging is a valuable technique
• Automated mineralogical interpretation methods are essential to deal with the volume of data
• Understanding the methods and processes behind the mineral outputs will assist geoscientists in applying NVCL HyLogger data to their specific problems with confidence
• Next speakers can show examples of applying HyLoggerdata
Conclusions
NORTHERN TERRITORY GEOLOGICAL SURVEY
• Andy Green (OTBC Pty Ltd) has contributed to much of this work, particularly CLS and TSA modelling work.
Acknowledgements
NORTHERN TERRITORY GEOLOGICAL SURVEY
Validation ML48 (2012)ID TSAT Min1 TSAT Min2 TSAT Min3 TSAS Min1 TSAS Min2 XRD Comments
19301 186.28 Hedenbergite-1 57% Augite-1 43% Aspectral Clinopyroxene, ? , Pyrrhotite, Mica,
Plagioclase, Chlorite, Amphibole, Quartz
Clinopyroxene matches Na-Esseneite,
Plagioclase matches Na-Anorthite, unknown may
be sulphide
15530 158.34 Hedenbergite-1 53% Diopside-1 47% Aspectral Clinopyroxene, Pyrrhotite, Amphibole,
Plagioclase, Mica, ? , Chlorite
Clinopyroxene matches Na-Esseneite, unknown
probably Pyrite or Hematite
10915 124.62 Augite-3 59% Diopside-2 23% Grossular 1
8
%
Riebeckite 100% Clinopyroxene, Amphibole, Mica, ? ,
Chlorite
Clinopyroxene matches Na-Esseneite, unknown
may be Garnet, Amphibole probably not
Riebeckite
39495 332.79 Albite-1 64% Quartz LH 36% Paragonite 100% K-Feldspar (35%-50%), Quartz (25%-
35%), Plagioclase (15%-25%), Mica (2%-
5%), Chlorite (2%-5%)
K-Feldspar probably Orthoclase, Plagioclase
probably Albite, Mica probably Biotite (definitely
not Paragonite)
39381 331.96 Quartz LH 58% Anorthoclase-2 42% Muscovite 100% Quartz (35%-50%), K-Feldspar (25%-
35%), Plagioclase (15%-25%), Chlorite
(5%-10%), Mica (2%-5%)
K-Feldspar probably Orthoclase, Plagioclase
probably Albite, no Anorthoclase, Mica probably
Biotite
16893 168.37 Ankerite 81% Quartz LH 19% Siderite 100% Calcite, Clinopyroxene, Plagioclase, ? ,
Quartz
Clinopyroxene matches Na-Esseneite, unknown
a minor constituent
16680 166.80 Siderite-1 58% Grossular-1 42% Calcite 100% Calcite, Garnet, Vesuvianite,
Clinopyroxene
Garnet probably Grossular
28913 256.01 Hedenbergite-2 56% Muscovite dbl 44% Muscovite 100% Clinopyroxene, Plagioclase, Mica,
Chlorite, Amphibole, Pyrite
Clinopyroxene probably Hedenbergite, Mica
probably Muscovite
36610 311.93 Microcline-3 69% Albite-1 31% Muscovite 51% Fe-Chlorite 46% Quartz (35%-50%), K-Feldspar (25%-
35%), Plagioclase (15%-25%), Chlorite
(5%-10%), Mica (<2%)
K-Feldspar probably Orthoclase, Plagioclase
probably Albite
38343 324.56 Quartz LH 67% Anorthoclase-2 33% Muscovite 100% Quartz (35%-50%), K-Feldspar (25%-
35%), Plagioclase (15%-25%), Chlorite
(5%-10%), Mica (<2%)
K-Feldspar probably Orthoclase, Plagioclase
probably Albite
38860 328.03 Quartz LH 63% Microcline-1 37% Muscovite 100% K-Feldspar (25%-35%), Quartz (25%-
35%), Plagioclase (25%-35%), Chlorite
(5%-10%), Mica (<2%)
K-Feldspar probably Orthoclase (definitely not
Microcline), Plagioclase probably Albite
Correct mineral Correct group Wrong group
NORTHERN TERRITORY GEOLOGICAL SURVEY
Sample ID: PU11BRS001
Hole ID: MURD001 Index: 19470XRD response: Quartz (>80%), K-Feldspar (?microcline) (2%-5%), Dickite
(2%-5%), Mica (2%-5%), Chlorite(<2%), Jarosite13 (<2%). Mica is possibly illite.
Chlorite peaks overlap with dickite. Jarosite only detectable in fine fraction
Conclusion: XRD confirmed dickite response.Allowing an extra mixture in TSA did not identify chlorite
Validating dickite
MURD001 has a mixed dickite / muscovite TSA
response. The dickite response is quite strong
(approximately 70% dickite; 30% muscovite here;
SRSS is around 75) but is this really dickite?
Checked with XRD.
Which wavelength region is best?
NORTHERN TERRITORY GEOLOGICAL SURVEY
Previous presentation at 2010 AESC (Huntington et al)
– Palygorskite (Lighthouse Gully Qld)
found to be zeolite (EDAX and XRD)
which was not then in TSA library
Since 2010, ongoing XRD validation carried out by Surveys to add confidence in HyLogger results
Mineralogical Validation of the NVCL via
external techniques
Sample HyLogger mineralogy XRD mineralogy
C110564 FeChlorite (60%), Kaolinite PX (40%) Muscovite (65%), Chlorite (35%)
C110565 Muscovite (80%), Kaolinite PX (20%) Muscovite (65%), Kaolinite (30%), Chlorite (5%), Goethite
C110566A FeMgChlorite (80%), Muscovite (20%) Chlorite (60%), Muscovite (40%)
C110566B Kaolinite PX (70%), Muscovite (30%) Halloysite (50%), Muscovite (35%), Chlorite (15%)
C110567 FeMgChlorite Chlorite (85%), Muscovite (15%)
C110568 Biotite (60%), Muscovite (40%) Muscovite/Biotite (70%), Chlorite (25%), Siderite (5%)
C110570 Biotite (60%), Muscovite (40%) Muscovite/Biotite (55%), Chlorite (40%), Siderite (5%)
C110571 Kaolinite WX (60%), NH Alunite (40%) Siderite (60%), Kaolinite (25%), Mica (5%), Chlorite (10%)
C110573 Dolomite Dolomite
C110574 Kaolinite (60%), FeMgChlorite (40%) Mica (40%), Kaolinite (40%), Chlorite (20%), Siderite, Ankerite
C110575 FeChlorite Chlorite (50%), Muscovite (50%), Calcite
C110576 Muscovite (50%), FeMgChlorite (50%) Muscovite (55%), Chlorite (40%), Calcite (5%)
C110577 Phengite (80%), Gypsum (20%) Chlorite, Mica, Rozenite, Gypsum/Melanterite
C110578 Muscovite (60%), Gypsum (40%) Muscovite (60%), Kaolinite (30%), Siderite (10%), Chlorite
C110579 Kaolinite WX Muscovite (60%), Kaolinite (30%), Siderite (10%)
C110580 Dolomite Dolomite (65%), Mica (25%), Kaolinite (10%), Siderite
C110581 Calcite Calcite (75%), Mica (20%), Chlorite (5%), Siderite, Mg-Kutnohorite
C110582 NH Alunite Mica (60%), Chlorite (40%), Siderite
C110583 Dolomite Mg-Kutnohorite
C110584 FeMgChlorite (80%), NH Alunite (20%) Chlorite (70%), Calcite (30%)
C110586 Calcite Calcite (80%), Chlorite
C110587 Dolomite (55%), Muscovite (45%) Mg-Kutnohorite (40%), Chlorite (25%), Mica (15%), Siderite (10%), Calcite (10%)
Validation RUL01 Alberton– MRT
NORTHERN TERRITORY GEOLOGICAL SURVEY
uTSA compared with XRD – mineral proportionsuTSAS give 66% dolomite, 34% gypsum with SRSS of 74.
Enabling an extra mixing level gives:
49% dolomite, 30% gypsum, 21% talc with SRSS of 34.
uTSAT gives 65% gypsum, 35% quartz
XRD: anhydrite 65 – 80%; dolomite 15 – 25%; gypsum, quartz, talc (2-5%); chlorite <2%